Thermodynamics of extraction of Am(III) and Eu(III) from different anionic media with Tri-n-octyl phosphine oxide
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G. Suresh
Abstract
Extraction of Am(III) and Eu(III) from NO3-, ClO4-, SCN- and NO3- + ClO4- media with tri-n-octyl phosphine oxide (TOPO) in xylene has been carried out at 15, 25, 30 and 35°C. Under the extraction conditions the species M(NO3)3·3TOPO, M(SCN)3·4TOPO, M(ClO4)3·4TOPO and MNO3(ClO4)2·4TOPO are predominantly extracted at all the temperatures (M=Am or Eu). The two phase equilibrium constant (log Kex) follows an order SCN- > NO3- + ClO4- > ClO4-> NO3-. Extraction enthalpies have been calculated in each system from the temperature dependence of the Kex. The thermodynamic parameters ΔG, ΔH and ΔS have been discussed and compared with other mono- and bidentate organophosphorus extractants for Am(III) and Eu(III) from same aqueous medium. The -ΔH values for the two-phase reaction follow an order NO3- + ClO4- > ClO4- > SCN- > NO3- for both metal ions. This has been explained on the basis of heat energies involved with the formation of ML3 complex (L being the anion used), the transfer of ML3 to the organic phase and the attachment of TOPO molecules, and also on the limiting partial molal volume of the anions.
© 2003 Oldenbourg Wissenschaftsverlag GmbH
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Articles in the same Issue
- Thermochromatographic studies of berkelium chlorides: BkCl3 and BkCl4
- Thermodynamics of extraction of Am(III) and Eu(III) from different anionic media with Tri-n-octyl phosphine oxide
- Influence of humic acid size on actinide complexation
- The role of oxidants in Pu-Th separation studies employing di(2-ethylhexyl)isobutyramide (D2EHIBA) as extractant
- Synthesis and properties of neptunium(VI,V) and plutonium(VI) pertechnetates
- Speciation of polonium released from molten lead bismuth
- Extraction separation of No-carrier-added astatine from bismuth target
- Enhanced extraction and separation of trivalent lanthanoids with 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone and dicyclohexano-18-crown-6
- Thermodynamic modeling of metal–ligand interactions in high ionic strength NaCl solutions: the Ni2+-oxalate system
- Influence of surface charge of an Fe-oxide and an organic matter dominated soil on iodide and pertechnetate sorption
- Concentration distributions of radionuclides in sediments along the Romanian sector of the Danube River and the Black Sea coast
